The invention relates to a combustion chamber of a gas turbine, comprising an external combustion chamber wall and at least one tile that is mounted at the same, as well as a base plate.
It is known in the state of the art to attach combustion chamber tiles to a support structure of the combustion chamber's external wall, which is also called a liner. On the side that is facing towards the combustion chamber, the combustion chamber tiles have a large number of effusion cooling holes. These effusion cooling holes serve for cooling the tile to counteract the high temperatures inside the combustion chamber. Further, a combustion chamber tile has at least one mixing air hole through which air from the space externally surrounding the combustion chamber (annular channel/annulus) is guided inside the combustion chamber so as to mix with the combustion phase and to lean the combustion. What is particularly achieved in this manner is a reduction of the NOx formation inside the combustion chamber. In addition to cooling through the effusion cooling holes, the tiles are often provided with a ceramic coating that serves as an insulating layer against the high temperatures inside the combustion chamber.
In the solutions known from the state of the art, the attachment of a combustion chamber tile at the exterior wall of the combustion chamber is carried out by means of setscrews. These represent integral parts of the tiles which are mostly formed as cast parts, and they are usually threaded. The setscrews are guided through a hole in the exterior wall of the combustion chamber and, starting from the outside, are fixated at the exterior wall of the combustion chamber my means of a nut.
Such configurations are already known from U.S. Pat. No. 6,145,319 A, EP 0 927 992 A2 or DE 102 14 570 A1, for example.
It has turned out to be a disadvantage of the known solutions that the material of the bolts creeps due to the high thermal loads acting on the bolts. Because of the creep of the material, the prestress of the bolt is decreased through the nut. This results in a loosening of the bolts, which in turn may also lead to a loosening of the tiles.
Another disadvantage is the fact that with the tiles usually being formed as cast constructions according to the state of the art, it is not possible or possible only to a limited extent to manufacture them by means of an alternative manufacturing method, namely by means of additive manufacturing. Such additive manufacturing methods may be selective laser sintering, direct laser depositioning or electron beam deposition welding, for example. The reason for the limited manufacturability of the already known constructions particularly lies in the fact that a cost-intensive horizontal manufacturing has to be chosen. Alternatively, an elaborate substructure for supporting the setscrew is necessary. Such substructure are material-intensive and protract the manufacturing process, and they also have to be removed from the tile after the manufacture. All that is cost-intensive, as well.